Door closing mechanism



Dec. 25, 1956 Filed Feb. 11, 1953 H. RING ET AL 2,774,987

DOOR CLOSING MECHANISM 3 Sheets-Sheet l I INVENTORS ATTORNEYS Dec. 25, 1956 ETAL DOOR CLOSING MECHANISM 3 Sheets-Sheet 5 Filed Feb. 11. 1953 mmvroxs g2, fl/wqx AT TORNEKS fi/mu' BY Ma a:

United States Patent i DOOR CLOSING MECHANISM Henrik Ring, Sierra Madre, Caiifi, and Arlington A. Ferguson, Toledo, Uhio Application February 11, 1953, Eacrial No. 335,268

2 Claims. ((11. 16-62) This invention relates broadly to door closing mechanisms or devices. More particularly, it has to do with a door closing mechanism of improved construction which will assure more positive and progressive return movement of a door to closed position after it has been swung from the closed position and then released.

The principal object of the invention is to provide a novel door closing mechanism which is adapted to move or cause the swinging movement of a door from an open position to the normal closed position within the door frame and whereby such movement will be steady and positive in effect with a controlled final slow-down until the door is closed with a positive action.

As herein disclosed, embodiments of a door closing mechanism, as constructed in accordance with the present invention, broadly comprise a compound lever and a fluid-containing casing. Within this casing, there are arranged, for reciprocal movement, a gear member and a substantially integral piston member. Actively associated with the piston is a compression-type spring which is adapted to develop a reacting pressure upon movement of the gear member and piston in one direction. The piston causes a'free exhausting flow of the contained fluid in one direction and subsequently, under the impetus of the spring, movement in an opposite direction although at a metered or governed rate of flow. There is thus afforded, through an operative association of the gear member with the compound lever, means whereby the piston will be caused to compress the spring as the door is opened; however, during closing of the door, and since the gear member and piston mechanically constitute one active element, the action of the spring to move the piston, while being governed by a metered flow of the contained fluid, will be transmitted in a steady and uninterrupted manner at all times to efiect closing of the door. Consequently, it becomes practically impossible for sudden air drafts or currents to propel the door, separately and in advance of its controlled movement, or in anyotherwise, produce noisome slamming or jerking of the door.

Another object of theinvention is to provide a door closing mechanism of the above character wherein novel means is provided to permit a rapid rate of exhausting flow of the contained fluid during movement of the piston in response to opening of a door and subsequently to progressively vary the flow rate when the door is closing whereby the piston will be moved by the compressed spring through the major part of its movement at a constant rate and until, by the provision of an especially constructed passageway, it is perceptibly slowed in its motion and then moved at a final accelerated rate to its closed position.

Another object of the invention is to provide within a door closing mechanism of the above character novel means for adjustably controlling the flow of a contained fluid from the exterior of said mechanism whereby modifications in performance can be easily and accurately made with dismantling of any of its other parts.

2,774,982 Patented Dec. 25,

ICC

A further object of the invention is to provide an actuating lever for a door closing mechanism which can be quickly and conveniently re-arranged to permit use of the said mechanism with a door intended to open or close in either direction (either right-hand or left-hand opening).

A further object of the invention is to provide means within a door closing mechanism of the above charac ter which continuously operates for either right-hand or left-hand operating doors, which means may be connected to a compound actuating lever in a simple and eificient manner.

A still further object of the invention is to provide a door closing mechanism which is embodied in a rugged, eificient construction, Well adapted to simple assembly and continuous performance without undesirable maintenance.

Other objects and advantages of the invention Will become more apparent during the course of the following description when read in connection with the acccmpanying .drawings.

In thedrawings, wherein like numerals are employed to designate like parts throughout the same:

Fig. l is a perspective view of a door closing mechanism, constructed in accordance with the present invention, in mounted relation to adoor;

Fig. 2 is a top view of the door closing mechanism;

Fig. 3 is an end view of the closing mechanism;

Fig. 4 is ,a top view of the closing mechanism, with the operator arms removed;

Fig. 5 is a vertical, longitudinal section of the mechanism, certain of the operative parts being located at one end of their'movement;

Fig. 6 is an enlarged vertical, transverse view of the contained gear mechanism taken on line 66 of Fig. 4;

Fig. 7 is a crosssectiona1 detail view of one fluid control passageway in the body of the door closing mechanism taken on line 77 of Fig. 5;

Fig. 8 is an enlarged fragmentary view of a restriction passageway, taken on line 8-8 of Fig. 5;

Fig. 9 is a cross-sectional view of one of the one-way ball-valves located in the piston of the mechanism taken on line 9-9 of Fig. 7;

Fig. 10 is ahorizontal, longitudinal view of the door closing mechanism taken on line Ill-10 of Fig. 3, certain of the operative parts being located at the opposite end of their movement as disclosed in Fig. 4;

Fig. 11 is a vertical, transverse sectional view taken on line 1111 of Fig. 10;

Fig. 12 is a cross-sectional detail view of the operator arms of the door closing mechanism, and

Fig. 13 i a plan view of the door closing mechanism when the same is employed on a door opening oppositely to the door shownin Figs. 1 and 2.

Referring now 'to the drawings, there is shown in Fig. l a door closing mechanism in mounted relation with respect to a door Ztiandthe frame 21' therefor. Generally speaking, the door closing mechanism, as constructed in accordance with our invention, consists of a casing or body portion 22, fixedly mounted on the door 2%), and a compound lever arm, generally designated by the numeral 2-3, which is in part or at one end operatively associated with the casing 22 and in part secured for pivotal movement relative to the door frame 21. By means of a flexible force contained within the casing 22, the door closing mechanism is adapted to return the door 20 to a closed position within the frame 21 once the door has been swung to a so-called open position and then released by the user. For this purpose, the compound lever arm 23 is formed by two members or arms-the radius arm, indicated at 24, being pivotally mounted on the door frame 21 by a bracket 25 while a crank arm, indicated at 26, is rotatably connected to the arm 24 and at its opposite end to elements contained within the casing 22, in a manner to be more fully described hereinafter.

The compound lever arm 23 is adapted to open and close elbow-wise in response to the swinging motions of the door and, since the radius arm 24 thereof is restrained to swing about a fixed axis, within the bracket 25, it operates to define an arcuate path through which one end of the component crank arm 26 will move while the opposite end of said crank arm is carried through an arcuate path of motion described about the axes of the hinges on which the door is hung. Briefly stated, this movement of the crank arm 26 induces, upon opening of the door, a compressive action within the casing 22 whereby, when the door 20 is released, a resultant expanding action occurs within said casing to return the door in a positive manner to its closed position relative to the frame 21. Thus the door, once it has been swung to an open position, may be released and will be returned to a closed position in a constantly controlled manner and without noisome slamming or jerking which is usually occasioned by sudden air drafts or currents.

The casing or body portion 22 of the door closing mechanism comprises a tubular body 27 which has bases or footed pedestals 28 at each end thereof. For the purpose of properly locating the door closing mechanism, the pedestals are formed to project laterally from a side of the body 27 and have countersunk openings therein for receiving suitable wood screws 29, as may be seen in Fig. 3, when mounted on the door 20.

The interior of the body 27 is formed to define a piston chamber 30, a gear chamber 31 and a horizontally disposed well 32. The chambers 30 and 31 are separated from one another and from the well 32 by walls 33 and 34, respectively, which are provided with apertures 35 for communication therebetween. The piston chamber 30 and the wall 36 thereof are of circular cross-section and the outer end of said chamber is tapped to receive a screwthreaded cap 37 to close the chamber. Immediately adjacent this threaded end of chamber 30, an annular chamber or groove 38 is formed in the wall 36 and at diametrically opposed areas in the vertical, axially disposed plane of the chamber 30, the groove is increased in width by semi-circularly relieved and cut-away venting portions 39 (Fig. 11). Both the groove 38 and the cut-away or relief vents 39 perform a specific function in the operation of the door closing mechanism as will be more fully hereinafter described.

The gear chamber 31 is open at its upper end and is closed by a cover-plate 40 and sealed by a suitable gasket 41. The cover-plate and gasket are secured on the body 27 by screws 42. The cover-plate is provided with upwardly and downwardly projecting bosses which form hubs 43 that are equally spaced from a medial vertical plane through the longitudinal axis of the body or casing 22. The hubs 43 support vertically disposed shafts 44 and 45 that are journaled in bearing sleeves 46 fitted into counterbores at the lower ends of the hubs. The lower ends of the shafts 44 and 45 are stepped into suitable sockets 47, axially aligned with the hubs 43 and formed in the floor 43 of the gear chamber. The shafts 44 and .45 carry spur gears 49 and 50, respectively, which are secured thereto by keys 51 (Fig. 6). The upper and outer end of each shaft is flatted to provide oppositely disposed, parallel surfaces 52 for rigid attachment of the crank arm 26 of the compound lever 23.

The pair of gears 49 and 50 are actively associated with a gear rack 53 and are provided for operation of the door closing mechanism with either a right or a lefthand opening door. While only one gear is operatively employed in either instance to produce movement of the rack 53, both of the gears function at all times to support and guide the rack in alignment with the axis of the piston chamber 30.

As shown in Figs. 2 and 6 for use with a right-hand opening door, the crank arm 26 is associated with the gear rack 53 through the shaft 44 and gear 49 while the shaft and gear 59 are inoperative although they may rotate in meshed relation with the rack and guide the rack in its movement. On the other hand, when it is desired to use the closing mechanism with a left-hand opening door, the arm 26 is removed from the shaft 44 and mounted on shaft 45, as shown in Fig. 13, so that the shaft 44 and gear 49 then rotate and serve to guide the rack. For assuring a rigid connection of the arm 26, the end thereof has a socket 54 formed therein which has corresponding surfaces to the flatted end surfaces 52 of either shaft 44 or 45. Preferably a set screw 55 is threaded into the wall of the socket 54 and tightly turned against the surface of the associated shaft to prevent the arm 26 from sliding up and off therefrom.

The gears 49 and 50 mesh with teeth 56 formed in the opposite vertical sides of the gear rack 53. The rack is maintained in substantial alignment with the gears by means of a finished boss 57 on the floor 48 of the gear chamber 31 and a downwardly directed boss 58 formed as a depending part of the cover-plate 41. The gear rack is formed at one end to provide a yoke 59 between the bifurcated ends 6i? of which the connector stem 61 of a piston 62 in the chamber 30 is located. While the gear rack 53 and piston 62 may be structurally considered to be an integral member, as herein shown the yoke 59 and piston stem 61 are interconnected by a screw 63 for simplicity of assembly.

Either of the gears, operating in response to turning of the crank arm 26 as the door 20 is opened thus constitutes the prime mover of the door closing device and, through the gear rack 53 and piston 62, will operate to compress a coil spring 64, located in the chamber 30 and interposed between the piston and the wall 33, as the piston is moved rearwardly within the chamber 30. However, when the door is released, the circumstances are reversed so that the spring may operate to actively move the piston forwardly toward its normally idle position adjacent the closure cap 37. In order to govern the expanding action of the spring 64, the several chambers of the body 27 are filled with a fluid, such as a light machine oil, which is forced to be displaced or exhausted from one side of the piston 62 to the opposite side through defined passageways which are adapted to restrict or meter this displacement to reduce the closing speed of the door to a continuous, gradual motion. The oil or fluid may be supplied to the interior of the body 27 through a filler hole 65 in the cover-plate 40 which is ordinarily closed by a plug 66.

The piston 62, for this purpose, has a conventional forward vertical wall 67 and an integral skirt or annular wall 63 substantially fitting the inner surface 69'of the chamber 30. Several passageways are formed in the vertical piston wall 67 which serve as self-acting one-way valves to permit flow of the fluid from the area, designated by the letter A, of chamber 30 into the area, designated by the letter B, when the piston is moved rearwardly or toward the wall 33. However, when the piston is moved forwardly, the so-called valves prevent the flow of the fluid from area B into area A thereby shunting the flow of fluid through a metering by-pass, indicated at C, and accordingly controlling the action of the spring 64 to assure gradual and continuous closing of the door. Equally spaced on opposite sides of the vertical longitudinal plane of the piston 62 are valved passageways 70 and between these passageways there is an additional passageway 71.

The passageways 70, as seen in Figs. 9 and 11, are substantially Z-shaped, having a horizontal passage 72 open to the rear of the piston wall 67 and to the lower end of a vertical chamber 73, and a horizontal passage 74 opening to the front of wall 67 from the upper end of said chamber, The chamber 73 may be formed [by vertically drilling downwardly in the wall 67 and then'closing the hole by a plug 75 the end of which is finshed to theouter annular surface of the piston. The chambers 73' con-- stitute valve areas and for this purpose a ball 76 is located therein so as to close communication from said chamber to the passage 72 (Fig. 9); however, the plug 75 is equipped with a tip or annular extension 77 which terminates substantially in line with the axis of passageway 74 to prevent the ball 76 from similarly closing communication to this passageway. Therefore when the piston is moved rearward, the fluid will enter passageways 72, rise in chambers 73 and lifting the balls 76 against tips 77, exhaust through passages 74 from the chamber area A to the area B.

The passageway 71 between the passageways 70 is formed by a vertical passage 78 opening at either end at the annular surface of the piston and a horizontal passage 79 opening to the rear face of the wall 67. The utility of the passageway 71 does not become effective until the piston, as it is moved forwardly and the passageways 70 are closed by the balls 76 in the chamber 73, reaches the vicinity of the groove 38 and relief areas 319. Otherwise the outlets of the passage 753 are blocked by the inner wall surface 69 of the chamber 30. This affords a relatively large passageway through which the fluid may escape and the sudden exhausting produces a final positive closing motion of the door.

The above-mentioned metering by-pass, designated C, comprises a longitudinally disposed passageway 80 which axially parallels the chamber 30. The passageway may be formed by drilling into a longitudinal boss 81 of the casing 27 and then closing the outerend thereof by means of a threaded plug 82 which for structural purposes then becomes an integral part of the casing. Vertically disposed passages 83 and 3d of a particular cross-section are formed in the boss 81 to intersect the passageway 80 and extend somewhat therebeneath where they terminate in lateral passages 85 and 86 respectively which open into the chamber 30 at ports 87 and 88 respectively in the annular wall 36 thereof. The passages 85 and 86 may be formed in a manner similar to the passageway 80 and their open, outer ends closed by plugs 82. Flow of the contained fluid from the chamber area A to chamber area B may thus be defined as through lateral passage 85, the vertical passage 33, the longitudinal passageway 80, the vertical passage 34 and outwardly through the lateral passage 86 and the port 88 thereof.

Within the vertical passages 83and 84, there are located suitable valve members 39 and 50 that operate to control the rate of flow through the metering by-pass C in either direction but more particularly the rate of fluid flow when the door is being closed and the fluid is exhausting from chamber area B back into chamber area A as the spring 64 is urging the piston 62 forwardly.

These valve members 89 and 90, each have a knob-end or handle portion 91, a threaded length 92, an annular shank 93 which terminates in a concavedly reduced portion 94 and a conical valve end 95 (Fig. 7). The passageways 83 and 84 are correspondingly formed at their upper, open ends with a tapped section 96, a cylindrical portion 7 and a terminus 98 of reduced diameter which is of conical formation to suit the valve end 95 and thus provide the valve seat 09. Preferably each valve seat 99 is located above the entry port into the lateral passages 85 and $6 and beneath the entry port into the longitudinal passageway 80 to provide a restricting orifice through which the flow of fluid may be controlled according to the position of the valve end 95 relative to the valve seat 99. To prevent undesirable loss of fluid along-the shanks 93 of the valve members 89 and 90, the'cy'lindrical portion 97 of the passages 83 and $4 is provided with an annular groove 100 for receiving a ring or type gasket 101.

As will be noted in Fig. 10, the lateral passage 85' is located at such a predetermined distance from the end wall of thechamber 30, formed by the cap 37, that a volume of fluid will still remain in the area B when the piston-62 has been moved so as to close off the port 88 of'the passage 86. This literally brakes the motion of the piston and acts as a cushion upon the closing of the door. In other words, as the door 20 approaches the frame 21, it is perceptibly slowed down to avoid slamming as it reachesthe fully-closed position. In order to permit this slower but continued movement of the door, a bleeder hole or duct 102 is located in the wall 36 and between the annular groove 38 and the passageway 80. The flow of fluid thus continues into the passageway 89 but at a materially reduced rate. As the piston reaches the end of its forward movement and approaches'the wall of the cap 37, the open ends of the passageway 71 are exposed to the areas of the relief vents 39 adjoining and opening into the groove 38. The remaining volume of fluid is then rapidly exhausted from the chamber area B through the vertical passage 78 and into the chamber area A through the horizontal passage 79 so that the energy of the spring 64 is arrested when the piston 62 arrives at the endof the chamber 30.

As shown in Fig. 3 and in better detail in Fig. 12, the compound lever 23 is adapted to be readily disassembled or adjusted to suit various installations. For this purpose, the radius arm 24 is formed by two members 103 and 104; the member 103 comprising a rod having a ball-shaped end 105 and an opposite threaded end 106, while the connector 104 has a tapped end, as at 107, and a socketed opposite end 108. More specifically, the ball-shaped end 105 of rod 103 is carried within a spherical seat 109 formed in the bracket 25. The bracket 25 has a base portion 110 which is provided at its opposite ends with countersunk openings 111 for receiving the wood screws 112 by which the bracket is securely mounted on the head rail of the door frame 21 (Fig. 3). Centrally disposed between the ends of the base 110 is a boss 113 which contains the spherical seat 109 and is horizontally slotted as at 114. The seat 109 is open to the rear surface of the bracket and the outer end of said seat is annularly formed and tapped to receive a threaded plug having a corresponding spherical seat 116. The member or rod 103 may thus be inserted into the bracket 25 and through the slot 114 until the ball end 105 engages the seat 109 after which the plug 115 is threaded into the bracket and a spherically chambered bearing surface will be created by the spherical seats 109 and 116 in which the ball end 105 may be freely turned and the rod 103 permitted swinging movements within the slot 114.

The threaded end 106 of the rod 103 is located in the tapped end 107 of the connector 104 and carries a locknut 117 by which the rod can be restrained from bodily turning. The opposite or socketed end 1% of the connector 104 contains a spherical chamber 118 which opens downwardly through a cylindrical wall portion 119. At the juncture of the chamber 118 and the wall 119 an annular cavity 120 is provided for receiving a split locking-ring 121. The chamber 118 is intended to receive the ball end 122 of a tapered shank stud 123 secured in the adjacent end 124 of the crank arm 2s.

Thus, in assembling or adjusting the component arms of compound lever 23, the crank arm 26 is mounted on the fiatted, upper end of the shaft 4-4 (for a right-hand opening door) and firmly secured thereon by the setscrew 55. The bracket 25 is then suitably mounted on the head rail of frame 21 by screws 112. The radius arm 24 is now positioned so that the socketed head 108 of the connector .104 is in vertical alignment with or disposed above the ball end 122 of stud 123. If the arm 24 is not of sufl'icient length, the lock-nut 117 is released from against the face of the tapped end 107 of said connector. The rod 103 may then be freely turned on the ball end 109 thereof in the bracket '25 until the spherical chamber 118 of connector 104 is vertically aligned with the stud 123. Upon inserting the ball end 122 thereof into the said chamber, the locking-ring 121 is spread until it snaps into place on the tapered shank 125 of the stud. A freely swin-gable and yet firm relation is thus effected between the component arms 24 and 26 of the compound lever 23. After returning the nut 117 to its locking position, the said arms will appear as is shown in Figs. 2 and 3.

If it is desired to use the door closing mechanism in connection with a left-hand opening door, the bracket 25 is located to the right of the arm 26, as shown in Fig. 13. The crank arm 26, for this purpose, is removed from the shaft 44 and is mounted in the same rigid relation on the shaft 45. The radius arm 24 is now adjusted in length to suit the modified position of the crank arm 26.

In the operation of a door closing mechanism, as constructed in accordance with the embodiments of this invention, the opening of the door will cause the compound lever 23 to open elbow-wise since the radius arm 24 will pivot in the bracket 25 and cause the crank arm 26 to be bodily carried in two defined arcuate paths. That is to say, as the end 124 swings in agreement with the end 108 of the arm 24, the opposite end of the arm 26, associated with the shaft 44 will move literally through an arcu-ate path generally described about the door hinges and will operate to rotate the shaft 44 and the spur gear 49 mounted thereon. This rotary motion now effects reciprocal movement of the gear rack 53 in a longitudinal direction so that the end thereof enters the well 32 which is intended for this purpose. As the door 2t) approaches an open position, the limit to which it can be swung will be determined by the lengths of the compound lever 23 and arm 26. In the event a fully open position of the door is reached, the arm 26 will be caused to describe an arc of sufl'icient magnitude that the gear 4-9, with which it is associated, will move the gear rack 53 into engagement with the end wall of the well 32. However, under normal circumstances of use and by the initial adjustment of the lever and arm, the radial swinging thereof will permit opening of the door 20 to a desired position without physical engagement of the moving gear rack 53 with the end wall of the well 32.

During opening movement of the door, the gear rack 53 and the integral piston 62 will compress the spring 64 against the casing wall 33. Movement of the piston 62 to the left as viewed in Fig. 10 toward a position as shown in Fig. 5 produces a reduction in volume of the chamber area A, with a consequent outflow of fluid through the port 87 into lateral passage 85 and through the valve seat 99 in vertical passage 83 to the passageway Sil from which it generally exhaust through the port 38 of passage 86 in the chamber area B. Simultaneously the compressive action enforced upon the fluid causes its flow through the passages 70 in the wall 67 of the piston thereby rapidly dissipating the compression of the fluid and permitting easy opening of the door.

When the door is released by the user, the spring 64 immediately becomes active to move the piston to the right toward the illustrated position of Fig. 10 and through the gear rack 53 to rotate the gear 49 and shaft 44 in the reverse direction. This is transmitted to the crank arm 26 which in turning employs the radius arm 24 to pull the door 26 toward its closed position. Now, as the piston is moved toward the chamber wall formed by the cap 37, the fluid in area B enters the passages 74 of passageways 70 but, in the chambers 73, forces the balls 76 against the entry to passages 72 thereby closing the one-way ball valves. The force of the expanding spring 64 thus forces the fluid to exhaust through the lateral passage 86, the longitudinal passageway 80 and outwardly from the port 87 of passage 85 into the cham ber area A. The rate of fluid flow past the valve member 90, or the valve end 95 thereof and the valve seat 99, accurately governs the rate of movement of the piston 62 and consequently the closing motion of the door 20. And since the gearrack is a substantially rigid connection between the door 20, through the compound lever 23, and the piston 62, no amount of undesired air current can cause the door to swing more rapidly than that produced by the pistons movement within the casing 22. As the vertical wall of the piston passes and closes off the port 88 of passage 86, the flow of fluid is materially reduced with a resultant gradual slowing of the doors motion. In fact the only egress remaining for the fluid to flow into the passageway is through the small duct 102 between the annular chamber 38 and the said passageway. The door accordingly approaches the frame 21 in a steady motion of reduced rate of speed. However, as the ends of the passage 78 in the piston 62 are moved into registration with the relief vents 39 (Fig. 11), the remaining volume of fluid still in compression between the piston wall 67 and the end of the chamber 30 is suddenly released to flow through said passage 78 to the opposite side of the piston 62 by the horizontal passage 79. Thus as the door 20 enters the frame 21, the final action of the spring 64, as evidenced by movement of the piston 62, is to positively close the door by a final rapid action.

In order that the closing of the door may be adjusted to suit any circumstances, the valve members 89 and 90 may be actuated to increase or reduce the area of flow past the valve seat 99 by raising or lowering the valve end 95. This may be accomplished by merely manipulating the knob 91 of either valve member and without resorting to the opening of any passageways with the usual loss of fluid. Since two valve members are herein provided a dual control is afforded whereby an exceedingly fine degree of fluid control may be attained.

It is to be understood that the form of the invention herewith shown and described is to be taken as a prefered embodiment of the same, but that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

We claim:

1. In a door closing mechanism, a casing mounted on the door, a substantially horizontally extending closed fluid-containing cylinder formed in the casing and having a chamber formed in one end thereof, an annular groove located in the opposite end of said cylinder and having enlarged portions, a piston mounted for reciprocation in said cylinder, means limiting movement of the piston toward said chamber, a bearing in said chamber, a door op erating shaft having one end journaled in said bearing and the other end extending outwardly from the casing, a compound lever having one end thereof pivotally mounted at a fixed point and the other end secured to the said shaft to rotate the same upon opening or closing of the door relative to said fixed point, a gear mounted on said shaft, a gear rack secured to said piston and disposed in said chamber in meshed relation with the gear to move the piston toward the chamber when the shaft is rotated, means maintaining said gear rack in said meshed relation with said gear, compressible means in said cylinder normally urging said piston away from the chamber, a fluid passage extending through said piston and communicating with said cylinder at opposite ends of the piston, valve means in the fluid passage for permitting free flow of fluid therethrough when the piston is moving toward the chamber and preventing flow of fluid therethrough when the piston is moving away from the chamher, a fluid by-pass in the casing paralleling the cylinder and terminating in spaced ports in the wall thereof, one of the ports being positioned between the chamber and the piston when said piston is at the limit of its movement toward the chamber and the other of the ports being positioned to be closed by the piston as said piston reaches a first position near said end of said cylinder,

adjustable valve means located in said fluid by-pass to restrict the flow of fluid therethrough, a restricted fluid passage extending between the fluid by-pass and the annular groove to permit a restricted flow of fluid from the cylinder to said by-pass when the second-named port is closed by the piston thereby retarding the movement thereof away from the chamber, a second fluid passage in the piston having ports normally closed by the wall of the cylinder and communicating with the end of the cylinder adjoining the chamber and means in said cylinder for communication between said second fluid passage and the enlarged portions of said annular groove as said piston reaches a second position near said end of the cylinder.

2. In a door closing mechanism, a casing mounted on the door, a door operating shaft having one end thereof journaled in said casing and the other end extending outwardly therefrom, a gear fixedly mounted on said shaft within said casing, a fluid-containing closed cylinder formed in said casing, a piston mounted for reciprocation Within said cylinder, a gear rack connected to said piston and operatively engaged with said gear, said gear rack having oppositely disposed teeth, a second shaft having a gear fixedly mounted thereon, the second gear being operatively engaged with the teeth of said gear rack oppositely disposed from the first-mentioned gear to maintain the gear rack in operative engagement with said first-mentioned gear, compressible means within said cylinder normally urging the piston away from the shafts and against one end of said cylinder, a compound lever having one end thereof pivotally mounted about a fixed point and the other end fixed to the first-mentioned shaft to rotate the same upon opening or closing of the door relative to said fixed point, means for permitting movement of the piston away from said cylinder end upon opening of said door, and means for permitting return movement of the piston toward said cylinder end upon closing of the door.

References Cited in the file of this patent UNITED STATES PATENTS 833,387 Henry Oct. 16, 1906 1,123,810 Shaw Jan. 5, 1915 1,595,722 Norton Aug. 10, 1926 1,674,756 Wuchert June 26, 1928 2,116,185 Bernhard May 3, 1938 2,528,904 Norballe Nov. 7, 1950 

